A stock or bond certificate on which the owner's details or other identifying information cannot be read. A mutilated security can be the result of damage, negligence, being printed incorrectly or other reasons, and must receive a guarantee of ownership from a third party to ensure there is no fraud.
This is simply a certificate that is damaged enough to be unreadable. To avoid fraud, this type of certificate cannot be transferred to the buyer unless a third party makes a legal promise that the certificate is legitimate. The guarantee of ownership comes from a transfer agent, a financial institution that maintains records of investors.